This invention relates to the field of organic chemistry, and more particularly to 2,4,6-triiodo-5-methoxyacetamido-N-methylisophthalamic acid and certain salts, acyl halides and 6thereof. These compounds are useful as x-ray contrast agents.
G.B. Hoey (U.S. Pat. No. 3,145,197/1964) disclosed 5-acetamido-2,4,6-triiodo-N-methylisophthalamic acid and its salts and their utility as components of aqueous x-ray contrast media. Subsequently, the coined terms "iothalamic acid" and "iothalamate" were applied to these compounds. A profuse literature relating to the radiological uses of these compounds has been published in succeeding years.
H. Priewe et al. of Schering AG (DAS 1,129,260/1962) disclosed the preparation of 3-acetamido-5-methoxyacetamido-2,4,6-triiodobenzoic acid and proposed its use as an x-ray contrast agent. They reported this compound as having an LD.sub.50 (i.v. in rats) of 16 g/kg.
Subsequently, H. Pfeiffer et al., also of Schering AG (DOS 2,118,219/1972 ), reported that, notwithstanding the favorable toxicity data in rats, this compound causes strong circulatory disturbances in dogs and man. The use, as x-ray contrast media, of aqueous solutions of salts of various 2,4,6-triiodoisophthalamic and other 2,4,6-triiodobenzoic acids with pharmaceutically acceptable cations, e.g., sodium, calcium, magnesium and alkanolamines, such as ethanolamine, diethanolamine and meglumine (N-methylglucamine), is well known to those skilled in the art.